Length-weight relationship and condition factor of thirteen fish species in the Tigris river before the construction of Ilisu and Cizre dams, Türkiye

Abstract

The Il & imath;su Hydroelectric Power Plant (HEPP), situated on the Tigris river in T & uuml;rkiye, began filling and forming a reservoir in 2021. In addition, there are plans for the construction of the upcoming Cizre HEPP. This situation has the potential to significantly impact the bio-ecology of fish species in the area. The research aimed to determine the length-weight relationships(LWR)and condition factors of thirteen fish species in the Tigris River: Arabibarbus grypus, Acanthobrama marmid, Alburnus sellal, Carassius gibelio, Cyprinion kais, Cyprinion macrostomus, Chondrostoma regium, Paracapoeta trutta, Capoeta umbla, Garra rufa, Squalius lepidus, Luciobarbus esocinus and Luciobarbus mystaceus, where Ilisu and Cizre dams reservoir will be formed. Length-weight relationships(LWRs)were determined using the formula W = aLb, where W represents weight and L represents length. Three types of lengths were considered: total length, fork length, and standard length. The exponent values(b)varied acrossthe species, ranging from 2.7875 for Acanthobrama marmid to 3.2214 for Carassius gibelio. The relationships between length and weight were found to be highly significant, as indicated by the R2 values, which were all greater than 0.80, except for Alburnus sellal and Garra rufa, which had lowervalues below 0.80. The condition factors were calculated using Fulton's condition factor(K)and relative condition factor(Kn). In all species, except for Arabibarbus grypus and Chondrostoma regium, the condition factors were greater than 1 (K>1). However, for Capoeta umbla and Garra rufa, the relative condition factor(Kn)was less than 1(Kn<1).